changes on pipeline mecanism: we now sample a different complexity for each transformations, this because when we use the same sampled complexity for all the modules 1/8 of the time we are close to 0 and we obtain an image very close to the source, we now save a complexity for each module in the parameters array

Known bugs:

- PersistentFactory() is almost certainly horrible at concurrent access
- Tests are never invalidated with PersistentStorage(), as they aren't written back to the database
- All files in Captcha/data are installed, including silly things like .svn directories and *~